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The Incredible Pluggable Packs a Big Punch in a Small Package

We focus on the role of optical networking in the evolution of next-generation networks quite a bit in this space, particularly from a long-haul, global perspective. And yet short-reach, point-to-point fiber optic connections are just as important in the larger scheme of web-scale and coherent networking, and that’s where pluggable client optical modules get an opportunity to shine.

For short-reach connections of less than 10 km, say among buildings and campus networks, pluggable modules offer interoperability, a small form factor and an attractive price point. They are especially useful for transporting high-speed Ethernet signals, as is necessary within and among data centers. And pluggable capacity is on the rise, with the data rates supported by pluggable form factors continuously increasing.

Optical networking company Ciena is a member of the 100G Lambda Multi-Source Agreement (MSA) group. The group has successfully demonstrated interoperability of its vendors’ Ethernet modules at 100 Gb/s over two km and 10 km of single-model fiber (SMF), as well as 400 Gb/s over 2 km of SMF. The data rate speeds are supported on a single wavelength, from one powerful, pluggable module.

Coherent solutions are also playing an important role in increasing the reach and capacity of pluggables. The Optical Internetworking Forum (OIF) specification for 400ZR, for instance, is set to support 400 Gb/s on a single wavelength of up to at least 80 km. The specification will make pluggables invaluable for applications like point-to-point data center interconnects (DCI). Additional advances are being made using higher coding gain FEC implementations in coherent DSPs to further expand the reach of pluggables, which would be useful for metro/regional applications.

Other potential applications for pluggables include shorter reach optical interconnect schemes like cable-MSO aggregation as well as access applications like 5G front-haul along with shorter-reach interconnects within a data center.

According to Ciena, the design of both semiconductor and electro-optical subcomponents of pluggable solutions is key to their evolution and widespread adoption. The design challenge involves balancing the need for low power consumption and a small form factor against demand for lifetime and environmental reliability.

The long-term success and development of pluggables will require vendors with strong foundational coherent optical networking technologies as well as advanced design skills, along with the financial strength and resources to meet the changing demands of web-scale networking. With groups like 100G Lambda MSA already focusing on interoperability, increased speed and efficiency, the future for pluggables in the coherent networking arena looks bright.

Web-scale Networking

The idea of Web-scale IT is more than just another 'hot' buzzword or problematic disruption. What started with data center operators has become mainstream thinking in large enterprises, and it's now driving changes in service provider operations, as well. Web-scale tools that allow application development to move quickly have also created some challenges for service provider networks.